1. Field of the Invention
The present invention relates to timelocks for bank vault doors and the like, and more particularly to timelocks of the kind adapted to be mounted on the inside of a bank vault door or the like to prevent the opening of the door by anyone outside the vault during selected delay intervals by blocking the path of movement of a snubber pin attached to the bolt bail.
2. Description of the Prior Art
Timelocks of this kind are well known in the prior art. Such prior art timelocks comprise three substantially identical clock movements, sometimes called "clocks," resembling highly refined kitchen timers, each of which is daily keywound and set by the user (e.g., a bank officer). Timelocks of this kind are generally provided with a manually operable arming knob or lever by means of which the user arms the timelock, i.e., prepares the timelock to block the path of movement of the snubber pin after the vault door is closed and locked, until at least one of the clocks fully runs down. When any one clock runs down in such prior art it displaces a longitudinally movable bar called the G-strip, thus releasing the arming lever to move from its operated state to its unoperated state and withdrawing the snubber bar from the path of movement of the snubber pin. When the path of movement of the snubber pin is thus unblocked it becomes possible to move the snubber pin, bolt bail and bolts by means of a hand wheel or the like and thus to unlock the vault door from outside the vault. The arming levers of timelocks of this kind are generally provided with lost-motion means which permit the arming lever to be manually returned to its unoperated state before the time set on any one of the three clocks runs out, whereby a person trapped in the vault may make it possible to effect his release from the vault by returning the arming lever to its unoperated position, whereafter a person outside the vault may release him by operating the combination lock and then operating the hand wheel or other bolt control means found on the outside of the vault door.
As is well known in the art, the space on the inside of typical bank vault doors for the mounting of timelocks is often stringently limited due to the presence of bolts, bolt bails, bolt actuating mechanisms, combination locks, and other mechanisms. Thus timelocks of this kind must in general be as compact as possible in order to permit mounting on the inside of many different vault doors without interfering with the operation of the other mechanisms just described. In addition, it is generally required by banking practice or law that three clocks be used in each timelock, in case of failure of one or two, and that each clock be capable of timing intervals as great as 120 to 144 hours. It follows necessarily that the daily setting of such prior art timelocks involves the winding of three clock-work mechanisms to precise settings on small, finely graduated dials, so finely graduated in some cases as to require the assistance of a built-in magnifying glass. Further since the clocks of such prior art timelocks are of the kind which run down to zero at the end of the interval set on the dial these clocks do not in general retain any indication of the magnitude of the previous time interval setting, though the same time interval setting may in fact be used from day to day, as in the weekday operation of banks. Yet further, the clocks of the prior art timelocks of this general kind begin to run down as soon as they are set.
Considering the above, it will be understood why in actual practice many instances have occurred in which, due to erroneous setting of prior art timelocks of this kind, it has been impossible to reopen the associated bank vault, necessitating the closing of the bank for an entire day or requiring that sufficient operating funds be procured from other banks at considerable cost in terms of additional security guards, armored transport, and the like.